Call to a member function isdeferred() on null

it gives me this problem on this "deferred" part. Can you help me? I'm new.

arguments;"Call to a member function isdeferred() on null"

        if ($instance->isdeferred()) {
            foreach ($instance->provides() as $service) {
                $manifest['deferred'][$service] = $provider;
            }

            $manifest['when'][$provider] = $instance->when();
        }

via Chebli Mohamed